"I charted religiously for 5 months, and we were doing the BD [baby dance] as soon as I saw that temp change and it just wasn't happening". L.
The above was a patient I saw a few years ago and I have had similar conversations with women since - I don't believe it is uncommon to use a BBT to completely miss your fertile window!
BBT stands for Basal Body Temperature, it just means the temperature of a body at rest.
Women are cyclical creatures. Unlike men who have a relatively stable hormone level, our hormones move through changes at different parts of our menstrual cycle, having an influence on our minds and bodies in all kinds of ways – one of which is our body temperature. BBT charting is simply measuring your waking temp every morning, and recording it on a graph or an app.
How does a BBT chart tell me about ovulation?
Remember learning about ovulation and fertility in high school? Probably not, because it probably wasn’t taught, but that’s an issue for another day.
Keeping it simple, estrogen is the hormone dominant in the first half of the cycle. Estrogen can be thought of as a yin hormone and is colder. After ovulation occurs, estrogen decreases and progesterone, a comparatively yang and warming hormone, increases.
If that makes your eyes glaze over, don’t worry. The key takeaway here is: a rise in progesterone indicates ovulation has occurred. A rise in progesterone is accompanied by a rise in temperature and will can be seen on a BBT chart. A chart with this temp rise is a biphasic chart, and it’s a good sign.
THE BIG QUESTION. Can you use BBT to time conception-sex?
It is vital to understand two key concepts;
By the time a rise in temperature has occurred, there is little or no time for conception-sex.
Here’s where BBT charting is useful.
No temperature rise? STOP. BREATHE. READ THIS BEFORE YOU PANIC:
There are SO many factors which can influence your BBT and make a chart appear off.
If you’re just not sure if you are ovulating, get yourself to a GP or pathology and request a progesterone blood test be taken seven days after you suspect you have ovulated. Timing is everything for this test and although the standard is to measure on “day 21” this does not equate with seven days after ovulation for everyone! Be specific about your request (or your demand if it comes to that).
If BBT charting tells me only that I HAVE ovulated, how do I predict my fertile window?
Watch this space… next post.